Solar Energy Storage Breakthrough at MIT

Photosynthetic plants are the inspiration for MIT Professor Daniel Nocera's invention for splitting water into it hydrogen and oxygen. Together with postdoctoral fellow Matthew Kanan, he discovered that by simply adding cobalt and phosphate to water and running a current through it, water could be split into its constituent oxygen molecules. This method is far cheaper than any previous method, opening the door for the efficient storage of electricity created by solar panels. The primary draw back to solar energy is that it is only available during sunlight hours and excess energy is expensive and impractical to store. But with this latest invention from MIT, if solar generated electricity can cheaply create and store hydrogen, then the hydrogen can efficiently be converted back to electricity with a fuel cell at night when power is needed. From Popular Mechanics:

The problem of how to store solar energ—or any energy at a large scale—is very real. Batteries are simply too expensive and don't yet have enough capacity. The Andasol solar thermal plant in Spain will test one interesting option later this year: Liquid heated by its mirrors will be stored in what is essentially a giant Thermos, so that the plant can continue to generate six hours of electricity each night. Abengoa recently announced a similar plant in Arizona; thermal storage will power the air-conditioning usage peak that continues after sunset in the Southwest.

Nocera's scheme has several advantages, though. Because it can work on a small scale, it's suitable for distributed power in homes.

The fact that they are using heat as a means to store solar energy in Spain is an indication of how sorely needed an efficient energy storage method is needed. Nocera's invention appears to just such a method and this is why it is being greeted with a significant amount of press and media attention.

First Solar, energy at $1.14 per watt

Yesterday I posted a blog entry about Nanosolar's manufacturing technique and their claim to manufacture at $1.00 per watt.  I also noted that the reality of the claim was not verified. Meanwhile, First Solar, the world's leading thin film solar panel company, claims to have manufactured panels at a cost of $1.14 per watt in the first quarter of 2008. The company predicts that costs bellow $1.00 per watt are achievable. Whereas Nanosolar uses a photovoltaic made from a copper-indium-gallium selenide (CIGS) semiconductor, First Solar uses a photovoltaic made from cadmium and tellurium (CdTe). Both elements are byproducts of the mining and production of base metals such as zinc and copper. These materials are present in abundant quantities to support multiple giga-watts of annual production.

First Solar announced $196 million in sales in the first quarter of 2008 up almost 300% from first quarter sales of 66 million in 2007. First Solar stock is currently trading at $265 per share.

First Solar will not be left without competition. GE has acquired a majority interest in PrimeStar Solar, a start-up that intends to compete in the CdTe solar panel market. Perhaps even more bullish on the technology than First Solar, the CEO of PrimeStar, Fred Seymour, says he sees a "clear path for getting to 15% conversion efficiency modules" and that the company "is well on track to beat 70 cents per watt without major breakthroughs." Unlike First Solar, PrimeStar Solar does not yet manufacture or sell a product. However, GE intends to achieve 1 billion dollars a year in solar energy revenue within three years.

Nanosolar, solar energy at $1 per watt

Nanosolar is a Silicon Valley start-up that manufactures thin film solar panels.  The video above shows Nanosolar's method of manufacturing solar cells by printing photovoltaic material directly upon sheets of aluminum at a rate of 100 feet per minute. Nanosolar claims that using this method they can manufacture solar cells at $1 per watt. If they can really produce solar cells at $1 per watt, it will represent a huge shift in energy economics. Nanosolar estimates that at $1 per watt, the over all cost of a system will be $2 per watt compared to a coal plant which has a cost of $2.10 per watt.

The average home uses about 8,900 kilowatt hours in a year. If a solar panel could generate electricity 24 hours a day, a one kilowatt solar panel would be sufficient to power the average American home. However, every place on earth averages 12 hours of daylight and many days are cloudy. Assuming a panel can average 6 hours of sunlight a day, a four kilowatt panel should handle the power needs of an average home. This type of array would generate excess electricity during peak hours on hot sunny days when electricity is in high demand which could be sold back to the grid in exchange for credits for energy used from the grid on cloudy days or at night.

At a price of $2 per watt a four kilowatt system would cost $8000. The cost of electricity, depending on where you live, is about $.12 per kilowatt hour. The average homes spends about $1068 on electricity per year.  So over the course of a decade, a Nanosolar system would save the average home $2,600 excluding financing charges and assuming that energy prices do not rise. If the panels last 25 years, as warrantied by the company, the average home would save approximately $18,700. However, energy prices are almost certain to rise and so the actual savings would be greater.

Unfortunately, it is impossible to verify if Nanosolar can actually manufacture at $1 per watt.   The company is not disclosing prices and claims that current manufacturing capacity is sold out for the next 12 months.